Surprises have, indeed, powerful effects. Psychologist Norbert Schwarz conducted a classic study where it was found that a small but pleasant surprise, such as finding 10 cents, uplifts a person’s mood. Schwarz repeatedly placed a coin near a copy machine where it can be easily seen. When the subjects who found the coin were surveyed shortly thereafter, their overall satisfaction with life was significantly higher than those who did not find the coin.
While the study was conducted at a time when a coin can buy more than it does today, the basic conclusion is that even a tiny, pleasant surprise can improve one’s disposition.